Duplications of additively acting genes in the evolution of a plant (Microseris pygmaea)

Summary Crosses betweenMicroseris pygmaea (10 pappus parts per fruit) andM. bigelovii (5 pappus parts) have revealed 10-determining genes that additively determine the average number of pappus parts in the hybrids. One or two such genes are found in different populations. Two independent duplications of the original 10-determining gene seem to have occurred.     

Beobachtung von Furchungsteilungen mit Chromosomen-Elimination in lebenden Embryonen der GallmückeHeteropeza pygmaea

Summary A method was developed which allows in vivo observation of chromosome elimination in early cleavage divisions of the gall midgeHeteropeza pygmaea.     

The selective accumulation of vitellogenin in the locust oocyte

Summary The selectivity of vitellogenin absorption by the locust oocyte was examined by comparing the uptake of vitellogenin and a haemolymph protein of similar molecular weight (MHP). Though both proteins occurred in the haemolymph at approximately the same concentration there occurred a 500-fold difference in accumulation of vitellogenin over MHP during a 24-h period. Surprisingly MHP did not accumulate in the oocyte during vitellogenesis.     

The effect of caerulein on epithelial growth in the mouse gall bladder

Summary Caerulein, a synthetic decapeptide, was injected into mice in order to study its effect on DNA-synthesis activity in the gall bladder epithelium. Histoautoradiography after the injection of labeled thymidine was used. Higher labeling indices were observed at 8, 12 and 24 h after caerulein injection. These data indicate that caerulein, apart from its cholecystokinetic effects, exerts a trophic effect on the gall bladder mucosa.Acknowledgements: this work was supported in part by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemene Spaar- en Lijfrentekas.     

Infertility of the hamster oocyte having matured in vitro]

The comparative study of fertilization, with the same sperm sample, of in vitro matured oocytes and freshly ovulated ones, shows a new aspect of mammalian oocyte maturation. While 80% of freshly ovulated oocytes are fertilized, in vitro matured eggs are not fertilizable. They present the ability to be penetrated by spermatozoa 4 to 6 hrs. only after HCG injection. This is therefore not on tubal influence but depends on an oocyte specific factor which appears during the end of intrafollicular maturation.     

Biochemical alterations in the oocyte in support of early embryonic development

Notwithstanding the enormous reproductive potential encapsulated within a mature mammalian oocyte, these cells present only a limited window for fertilization before defaulting to an apoptotic cascade known as post-ovulatory oocyte aging. The only cell with the capacity to rescue this potential is the fertilizing spermatozoon. Indeed, the union of these cells sets in train a remarkable series of events that endows the oocyte with the capacity to divide and differentiate into the trillions of cells that comprise a new individual. Traditional paradigms hold that, beyond the initial stimulation of fluctuating calcium (Ca²⁺) required for oocyte activation, the fertilizing spermatozoon plays limited additional roles in the early embryo. While this model has now been drawn into question in view of the recent discovery that spermatozoa deliver developmentally important classes of small noncoding RNAs and other epigenetic modulators to oocytes during fertilization, it is nevertheless apparent that the primary responsibility for oocyte activation rests with a modest store of maternally derived proteins and mRNA accumulated during oogenesis. It is, therefore, not surprising that widespread post-translational modifications, in particular phosphorylation, hold a central role in endowing these proteins with sufficient functional diversity to initiate embryonic development. Indeed, proteins targeted for such modifications have been linked to oocyte activation, recruitment of maternal mRNAs, DNA repair and resumption of the cell cycle. This review, therefore, seeks to explore the intimate relationship between Ca²⁺ release and the suite of molecular modifications that sweep through the oocyte to ensure the successful union of the parental germlines and ensure embryogenic fidelity.     

Refeeding of mice after fasting stimulates cell renewal in the gall bladder epithelium

Summary The effect of refeeding of mice after a fasting period on the uptake of 3H-thymidine and on mitotic activity in the gall bladder epithelium was studied by histoautoradiography. A significant increase in both DNA synthesis and mitotic activity was observed after 12 h of refeeding.Acknowledgments. This work was supported by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek and by the Algemeene Spar-en Lijfrentekas.     

The nucleocytoplasmic distribution of 3-O-methylglucose in the amphibian oocyte.

Ultra-low temperature microdissection was employed to determine the in situ nucleocytoplasmic distribution 3-O-methylglucose in the amphibian oocyte. The nucleocytoplasmic partition ratio, Kn/c, for this non-metabolizable monosaccharide was 1.54 +/- 0.08. The observed asymmetry could be explained by the differential solubility of the solute in the water of the nucleoplasm and the cytoplasm.     

Environmental regulation of oocyte growth in the bay scallopAequipecten irradians Lamarck

Zusammenfassung Temperatur- und Futtereinfluss auf das Gonadenwachstum von Winter- und SommerkammmuschelnAequipecten irradians Lamarck.     

Mechanism of in vitro gall induction inZizyphus jujuba Lamk.

Summary Zizyphus jujuba Lamk. stem galls incited byEriophyes cernuus Massee were induced aseptically on stem segments cultured on auxin and kinetin-free modifiedMurashige andSkoog's nutrient medium by 1. gall callus graft, 2. gall tissue extract and 3. incorporation of NAA into the medium.     

Nuclear lamellae in the germ-line cells of gall midges (Cecidomyiidae,Diptera)

Summary Lamellar structures in oogonial and spermatogonial cells of gall midges were found to form a complicated system of intranuclear compartments inside which all heteropycnotic chromosomes present in the germ-line cells of these insects are located. In this way, the heteropycnotic S-chromosomes are separated by the nuclear lamellae from the remaining, decondensed chromosomes (E-chromosomes) of the interphase germ-line nucleus.This investigation was supported in part under Contract DPKBN/52/76-II.1.3.10. with the Polish Academy of Sciences.     

IdentifyingY chromosome in interphase nuclei of the human brain

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The nucleocytoplasmic distribution of 3-0-methylglucose in the amphibian oocyte

Summary Ultra-low temperature microdissection was employed to determine the in situ nucleocytoplasmic distribution 3-0-methylglucose in the amphibian oocyte. The nucleocytoplasmic partition ratio, K_n/c, for this non-metabolizable monosaccharide was 1.54±0.08. The observed asymmetry could be explained by the differential solubility of the solute in the water of the nucleoplasm and the cytoplasm.Supported in part by an N.I.H. General Research Support grant to the George Washington University Medical Center.Acknowledgments. The author wishes to thank Mr T. Poandl for skillful technical assistance.